The primary goal of the Gene Targeting core will be to make available to the investigators of individual projects all available expertise, facilities, techniques and technical support required for generating /-/p/ttargeted mice, knockout/knockin mice and BAC transgenics. In addition, the core will provide reagents and advice on how to construct plasmids for use in Hprt targeting. In the case of knockout/knockin and BAC transgenic approaches, the core will also provide technical expertise in constructing targeting vectors.